Extrusion-based concrete 3D printing is getting broader attention in academia and industry. However, the larger interconnected pores at the interlayer region reduce the mechanical integrity and durability performance of 3D printed concrete elements. The present study investigates the influence of layer improvement techniques on the transport properties of 3D printed elements. Printed concrete wall elements were prepared with and without fresh cement paste applied in between the layers. The transport of chloride and moisture was investigated by measuring the non-steady-state migration coefficient and the conductivity. It was observed that the application of fresh cement paste at the interlayer decreased the migration coefficient as compared to the printed samples without cement paste in between the layers. The study gives further insights into the transport of ions through the interconnected interlayer region and the influence of the interlayer bond improvement technique on the transport properties
